Correct blower size for Gen VI 540?????????
 

iron heads and with or without intercooler..........

Roots style?

Yeah......

8-71 works well

What cam???? 8 or 8.5:1 pistons????

Bang for buck an 871 would be very good (436 cid per rev). A 671 (411 cid per rev) would work but you would most likely have to spin it slightly faster for equal amount of boost. I have a couple documents I can send you on supercharging (with marine supecharging included) that may be a good guide. What is your email?